US2395639A - Process for separating minerals by flotation - Google Patents

Description

.such complex operations practicable.

Patented Feb. 26, 1 946 2,395,639 I raocass FOR snrana'rrnc am s BY rLo'ra'rroN Louis 'il. Morison, Alhambra, and Orson Sutler Shepard, lPalo Alto, Caliifl, assignors to Petrolite Corporation, Ltd, a corporation of Delaware No Drawing. Application April 20, 1943, Serial No. 483,792

Claims.

This invention relates to separating minerals by froth flotation, and particularly to separating metallic minerals. 1

One object of our invention is to provide a novel process for separating minerals or ores into their more valuable and their less valuable comonents, by means of a froth flotation operation.

Another object of our invention is to beneficiate ores, particularly of metallic minerals, by apsuch finely ground ore, which mass or pulp usually contains a major proportion of water and only a. minor proportion of finely-ground ore;

subject such pulp to the action of a highly speciflc chemical reagent in a flotation machine or flotation cell, in the presence of a large amount of air; and recover the valuable constituents of the ore from the mineralized froth which overflows from the flotation cell. Many variations of this basic procedure have been developed, including the use of different types of flotation cells, different procedures of combining individual operations into different flow sheets to float sue.-

components, etc. The chemical side of the operation has likewise been varied greatly to make In addition to reagents adapted to collect the ore values in the froth (collectors), other reagents for improving the frothing characteristics of the flotation operation (frothers) or for selectively improving or retarding the flotation of individual members among the valuable components of the ore (activators or depressors) have been developed. The characteristics of the chemical reagents that have been used in the flotation operation differ greatly, until it may be said that a reagents flotation possibilities may best be determined by actual test in the process.

The process which we have discovered and which we believe to be novel comprises the" use of a reagent of a unique type-in a flotation process for the recovery of valuable constituents of minerals or ores. ,Our reagent comprises broadly a mixture of a blown fatty oil and a petroleum body. In some instances, we have found, the

blown fatty oil in such mixture may be profitably replaced in part by a sulfonated fatty body of a particular type, th improvement in results being so great as almost to constitute a separate invention.

Blown fatty oils, and particularly blown castor oil, have long been known and have been used in various arts, including the demulsiflcation of petroleum oils. In general, they are produced by the action, on a fatty oil or fatty acid, of an oxygen-containing gas, commonly air, and usually at somewhat elevated temperatures. In characteristics, they range from relatively low-vise cosity, light-colored liquids to nearly black liquids whose consistency may best be defined as semi-- livery. We prefer to use blown castor oil as the preferred ingredient of this type in our reagent.

We have found that variations in the nature of the blown fatty oil affect the results to some degree. We prefer to employ a blown oil of the drastically oxidized typ similar to that de scribed in U. S. Patent No. 2,023,979 to C. N. Stehr, in producing our reagent. But we have found broadly that mixtures comprising blown fatty oils and petroleum bodies, and mixtures comprising suchcomponents plus a sulfonated fatty body y of the kind described below, are valuable flotacessively and separately at number of valuable tion reagents; We prefer to use the blown fatty oil and the petroleum body comprising our reagent in proportions of 1:4 and 4:1. In some instances, the best results have been obtained by the use of reagents comprising substantially equal proportions of such two ingredients.. On the other hand, mixtures in the proportions of 1:9 or 9:1 have sometimes been most useful. Where a sulfonated fatty body of the kind described below is used to replace a part of the blown fatty oil, the above recited proportions still apply, the proportion then being taken betwen the petroleum body and the sum of the fatty bodies.

It has long been known that various animal, vegetable, and marine 'oils can be blown or oxidized, so as to yield materials which difier in chemical and physical properties and characteriswerejderifve dl The oxidation process is generally conducted by means of moist or dry air, ozone,

ozonized air, or a mixture of the same. It may be conducted at atmospheric pressure, or may ate, or may consist of organic material, such as alpha pinene or the like. Oxidation may be conducted in a relatively short time, such as 20 hours, or may require 200 hours ormore.

Patents which describe conventional blown oils or conventional methods of making various blown oils for various purposes include the following: U. S. Patent No. 1,929,399, dated October 3, 1933, to Fuchs; U. S. Patent No. 1,969,387, dated August '7, 1934, to Tumbler; U. S. Patent No. 2,023,979, dated December 10, 1935, to Stehr; U. S. Patent No. 2,041,729, dated May 26, 1936,. to Seymour; and U. S. Patent No. 1,984,633, dated December 18, 1934, to De Groote and Keiser.

Insofar that the material or composition we prefer to use as a, component of the flotation agent of our process is derived from blown castor 011, an effort will be made to describe said material or compound in considerable detail. Mild oxidation of castor oil (see "Chemical Technology and Analysis Of Oils, Fats and Waxes, by Lewkowitsch, 6th edition, vol. 2, p. 406) produces relativelysmall modiflcationsin certain important chemical indices, such as the iodine value, the acetyl value, and the saponification value. If drastic oxidation takes place," either b continued mild oxidation from the: very beginning of the reaction, or as induced by either a higher temperature of reaction, or by the presence of a catalyst, such. as alpha plnene, manganese ricinoleate, etc., then one obtains an oxidized oil having characteristics which clearly indicate that drastic oxidation ha taken place. These indices of drastic oxidation are a. relatively low iodine value, such as 65 or less, which may be as low as 40 or thereabouts; an acetyl valuecf approximately 160 to 200; an increased viscosity; a specific gravity of almost 1, or even a trifle over 1 at times; and in absence of other coloring matte a deep orange to deep brown color.

Drastically oxidized castor oil can be prepared by well known methods, or such products can be purchased on the open market under various trade names, such as blown castor oil," "bodied by direct oxidation of the various fats and oils,

but also by direct oxidation of the fatty acids.

to Hinrichs. Reference is also made to polymerized castor oil or'similar oils of the kind disclosed in U. S. Patent No. 2,114,651, dated April 19, 1938, of Ivor M. Colbeth. It might also be desirable to point out that the expression blown oil," as herein used, contemplates blown unsaturated liquid waxes, such as blown sperm oil. -It is understood that lnthe appended claims the expression blown fatty oil" is used in its broad sense to include all the various materials, such as esterifled blown fatty acids.

- A drastically oxidized castor oil of the above kind may, for example, have approximately the following characteristics:

Acid number 13.2 to 25.0 Saponiflcation number 230.5 to 274.0 Iodine number 43.5 to 55.0 Acetyl number 164.0 to 192.0 Hydroxyl value 188.0 to 220.0 Percent unsaponifiable matter.. 1.1 Percent nitrogen 0.0 Percent so: 0.0 Percent ash Trace Another variety of drastically oxidized castor lt is our preference to use blown oils, rather than blown fatty acids. We particularly prefer to use blown vegetable oils, such as blown cottonseed oil. .blown corn oil, blown soyabean oil, blown rapeseed oil, and especially. blown castor oil. Cur

preferred blown oil is a blown castor oil, which has been blown somewhat more drastically than indicated by the indices above recited. and which has been blown just short of the stage which produces semi-livery oils, as described in the aforementioned Stehr Patent No. 2,023,979.

The sulfonated fatty body which may comprise a component of our reagent, while obtained by the broad process of reacting sulfuric acid on a fatty acid or a fatty oil, is not an ordinary sulfonated oil. It is neutral or slightly alkaline to methyl orange indicator, which means that the carboxyl group present is substantially un-neutralized, whereas ordinary sulfonated. fatty oils are neutralized in the carboxyl group to an important degree, and are freely water-soluble becauseof their content of salts of fatty acid residues. the ordinary commercial neutralized type to be distinctly unsuited for use in our process, as they tend'to react with calcareous Emue minerals 'and float. such undesirable components of the Blown ricinoleic acid may be derived in the mannot indicated in U. 8. Patent No. 2.034.941. dated I March 24, 1936. to De Groote, Kaiser ond'wirtel. It should be noted that blown oils in the broad generic sense herein employed include not only the products derived by oxidation, but. also the products de'rivedby polymerization. Reference is madeto polymerized .ricinoleic acid described ores being treated. Our suifonated fatty oil contains only small amounts of water, commonly sulfcnated fatty oils are, in the free state, dibaaic acids, havin: a stroncly acidic hydrosen atom inU. S.P,at,cnt Ifo.'1.901,163, dated March 1.1933, 76' present in an acidic sulfate or sulfonic map, a

We have found sulfonated fatty oils of well as a weakly acidic hydrogen atom in the carboxyl group. I When such compounds are neutralized to methyl orange indicator with any suitable base, like caustic soda, potassium hydroxide ammonia, or triethanolamine, or the'like, only the strongly acidic hydrogen atom is replaced. Further addition of the base results in replacing the carboxylic hydrogen atom. The salts, when these compounds are neutralized only to methyl orange, are known as acid salts. Our process contemplates the use of a mixture containing a sulfonated fatty acid or sulfonated fatty oil, in

which the carboxyl group is not neutralized, in

contradistinction to neutral salts, except to the extent that there might be a relatively slight over-neutralization. Sometimes the acid salts of these compounds decompose in time, when neutralized with ammonia, so that they may exhibit some acidity to methyl orange. This does not destroy the utility of the material as an ingredient in the reagent of our process but the acidity exhibited may result in an unfavorable corrosive action on metal surfaces with which the reagent comes in contact. The sulfonated fatty acid or the sulfonated fatty oil will also contain nonsulfo. fatty materials, as is well understood in the art. The percentage of sulfur-containingacidic materials in sulfonated fatty bodies varies widely. We prefer to employ only those sulfonated fatty bodies that contain a minor proportion of sulfurcontaining acidic materials, the sulfonated fatty ingredient of our reagent usually producing at best, only a poor water dispersion when tested in absence of the other ingredients of the reagent. Organically combined sulfur trioxide preferably does not exceed 6% of the sulfonated fatty matter on an anhydrous or active matter basis.

.The petroleum body included in our reagent may be selected as desired. In some instances. crude petroleum oil itself is satisfactory; in other cases, gas oil, kerosene, gasoline, or other distillate is to be preferred. We prefer specifically to employ the petroleum distillate sold commercially as stove oil, as it appears'to have, in addition to having desirable properties as used in our reagent for floating minerals, certain desirable physical properties, i. e., it is relatively stable and non-volatile, it is relatively limpid, and it is relatively non-flammable; As an example of the specifications of such a stove oil, we give the following:

The flotation agent contemplated for use in our process is prepared by'simply mixing the blown fatty oil and the petroleum body, or the blown fatty oil, the sulfonated fatty body, and the petroleum body, in the desired proportions. The reagent so compounded is used in the ordinary operating procedure of the flotation process.

In some instances, the components of the mixture are compatible and combine into a perfectly homogeneous liquid reagent. In other in-- stances, they are more or less incompatible, and

. tend to separate or stratify into layers on quie s cent standing. In instances where the ingredients are capable of making a homogeneous mixture, the reagent may be handled and used without diiiflculty. If anon-homogeneous mixture results when the desired proportions are employed, a number of expedients may be resorted to to obviate the dimculty. For example, since it is common to include the use of a frothing agent in many flotation operations, the collector which comprises our reagent may be homogenized by being combined with a mutual solubilizer in the form of the desired frother, e. g., cresylic acid, pine oil, terpineol, one of the alcohols manufactured and used for froth promotion, like the duPont alcohol frothers, etc. If such mutual solubilizer is incorporated in or with the abover mechanically, as by a beater or agitator, im-

mediately before injecting it into the mineral pulp which is to be treated forthe recovery of we have employed with favorable results, we recite I the following, without being limited to the exact compositions shown:

Example 1 Reagent X-354 is a mixture of 60 parts of a drastically oxidized castor oil of the kind described above and 40 parts of stove oil.- This reagent, on a lead-zinc ore, behaved very much like potassium ethyl xanthate, which was highly effective on that ore. The froth, using reagent X-354, looked clean and was heavily laden with galena, in the lead flotation run. The froth was similar to that obtained using the xanthate reagent; and X-354 appeared equally powerful on the freshly-ground ore sample. Because of its lower cost, reagent X-354 would have an economic advantage over the higher-priced xanthate reagent.

Example 2 A reagent was prepared fromdrastically oxidized castor oil, sulfonated castor oil neutralized just to the methyl orange end-point. and stove oil, the proportions of, blown oil, sulfonated oil, and stove oil being approximately 5:4:11. This reagent was homogenized by the addition of secondary butyl alcohol, using 1.5 parts of the alcohol for 20 parts of the above mixture. The homo geneous reagent so prepared was used in floating a lead-zinc ore from Broken Hill, Australia. This ore also contained quartz, calcite and chalcopyrite, and is typical of a reasonably dimcult lead-zinc ore. The above reagent gave a much higher grade lead concentrate than did potassium ethyl xanthate, and neariy as high an economic lead recovery. It floated .very little gangue, the

' aleno appearance.

was used, was not quite so clean; and the froth,

mineral-bearing froth having a clean, metallic The froth, when xanthate when a water-soluble neutralized sulfonated castor oil was used, was definitely not as clean as in the other two cases. The neutralized sul= fonated castor oil gave definitely poor results on this ore, producing a viscous, slow-breaking dirty agent used in these runs floats chalcopyrite. The reagent was found to float sphalerite, activated by copper sulfate, satisfactorily. It was found not to float clean pyrite in the absence oi. copper sulfate.

. whereas potassium ethyl xanthate floats both copper sulfide and pyrite, unless a pyrite depressor is present in the cell. This difi'erence bet" zen the experlmentalr'reagent and the xanthate is of imp rtance in some copper flotation operations.

. Example 3 Reagent 'X-37l is a mixture of 1 part drastically oxidized castor oil of the kind described above and 9 parts stove oil, mixed with parts of terpineol, to incorporate the frother and collector A in a single homogeneous reagent. This reagent,

when applied to a lead-zinc ore from Broken Hill, Australia, appeared to have to an exceptional degree the property of collecting galena without collecting SDhalerite, without adding a depressor to prevent the flotation of the zinc mineral.

Example 4 Reagent 2-372. is similar to the reagent recited under Example 2 above, except that the blown oil-sulfonated oil-stove oil mixture (proportions, 5:4:11) was mixed with an equal weight of terpineol before use. Reagent X-373 comprises a mixture of the blown oil, sulfonated oil,

A reagent was prepared from a drastically oxidized castor oil, a sulfonated castor oil, -and a stove oil, of the kind described above, the proportion of blown oil, sulfonated oil and stove oil being approximately 7:3:10, and the stove oil containing about 20% of aromatic petroleum bodies. This reagent was mixed with about 5% of secondary butyl alcohol, and was used in such homogeneous admixture as a flotation reagent. It

was effective in recovering values from a Utah lead-zinc ore, when applied in the regular flotation procedure.

Theforegoing examples show the effectiveness of several examples of our flotation agents which are materially diflerent' in percentage composition, yet all of which embrace the basic concept of our invention. These examples show that our reagents are eflective in floating galena, sphalerite, and chalcopyrite, respectively under proper operating conditions. They show that the reagent may contain a preponderance of blown oil and a minor proportion of sulfonated oil, or vice versa. They showthat the proportion of fatty materials to petroleumbody may be varied widely. They show that asuitable frothermay be incorporated into the reagent to produce a single homogeneous reagent combining the properties of collector and frother.

The operative steps employed in practicing our process are those of-the ordinary flotation process as widely usedcommerclally today. However, for sake of example we have set forth below one "typical procedure, employing a lead-zinc ore,

without intending to be limited to that procedure.

' It is understood that various of the steps recited maybe modified, amplified or eliminated, as deasoaose sired, without departing from the spirit of this invention. The ore to be treated i first dryground to minus GE-mesh in-size, a screen analysis showing the following range of sizes:

, Per cent I Plus mesh Trace 65-80 mesh 2 -100 mes 10 -150 mesh 18 -170 mes 5 -200 mes 11 Minus 200 mesh 54 Total 100 erite was then activated by the addition of copper sulfate, 1.2 lb./ton of ore, and a rougher-cleaner operation was conducted to float the-zinc mineral, using the collector in the proportion of 0.02 lb./ton of ore in each cell. In some of the runs, a zinc depressor, such as sodium cyanide or zinc sulfate, or'both, was required to be used at the rate of a. fraction of a pound per ton.

One distinct advantage that our reagents enjoy over the flotation reagents now in commercial use is that they are less expensive to produce. Therefore, even in instances where they are not technically the equal of such reagents (on a pound-ior-pcund basis) it is frequently desirable to substitute them for suchmore expensive reagents. The flotation agents of our invention may be used in conjunction with other flotation reagents, e. g., xanthates, and do not destroy their effectiveness. In some instances, it is desirable to use our flotation agents in the rougher cell operation and use the xanthate to recover the values in the cleaner cell. In other instances, the two reagents may be used in a single operation in a single cell.

We claim:

1. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector comprising a mixture of a blown fatty oil and a petroleum body.

2. In a froth flotation process for the beneflciation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector comprising a mixture oi a. blown fatty oil, a petroleum body. and a mutual sclubilizing agent.

3. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore,-and agitating and aerating the pulp in the presence of a collector comprising a mechanically homogenized mixture of a blown fatty oil and a petroleum body.

4. In afroth-flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector comprising amechanically homogenized mixture of a pulp in the presence of a collector comprising a mixture of a blown vegetable oil, a petroleum body, and a mutual solubilizing agent- 6. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a mechanically homogenized mixture of a blown vegetable oil and a De-' pulp in the presence of a collector comprising a mixture of a blown castor oil, a petroleum body, and a mutual solubilizing agent.

9. In a froth flotation proces for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and'aerating the pulp in the presence of a collector comprising a blown castor oil and a petroleum body.

10. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a, collector comprising a mixture of a castor oil blown just short of the semi-livery state and a petroleum body.

11. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector comprising a mixture of a castor oil blown just short of the semi-livery state, a petroleum body, and a mutual solubilizing agent.

12. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector comprising a mechanically homogenized mixture of a castor oil blown just short of the semi-livery state'and a petroleum body.

13. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of'the ore, and agitating and aerating the pulp in the presence of a collector as recited in claim 1, the collector including a sulfonated fatty body which is substantially unneutralized in the carboxyl group. i

14. In a froth flotation-process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector as recited in claim 2, the collector including. a sulfonated fatty body which is substantially'unneutralized in the carboxyl group.

15. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector a recited in claim 3, the collector including a sulfonated fatty body which is substantially unneutralized in the carboxyl group.

16. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector as recited in claim 7, the collector including a sulfonated castor oil which is substantially unneutralized in the carboxyl group.

17. In a, froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore', and agitating and aerating the Y pulp in the presence of a collector as recited in claim 8 the collector including a sulfonated castor oil which is substantially unneutralized in thecarboxyl group.

19. In a froth flotation process for the beneficiation of metallic sulfide ores, the steps of forming a pulp of the ore, and agitating and aerating the pulp in the presence of a collector as recited in claim 10, the collector including a sulfonated castor oil which is substantially unneutralized in the carboxyl group.

20. In a froth flotation process for the beneflcia tion of metallic sulfide ores, the steps of forming apulp of the ore, and agitating and aerating the pulp in the presence of a collector as recited in claim 11, the collector including a sulfonated castor oil which is substantially unneutralized in the carboxyl group.

LOUIS T. MONSON. ORSON cum